Air moving apparatus



July 21, 1942. J. M. FUNK AIR MOVING APPARATUS 4 Sheets-Sheet 1 Filed Feb. 19, 1940 INVENTOR. BY Fania, .%4 9/ yW I V ATTORNEY}.

J.- M. FUNK AIR MOVING APPARATUS July 21, 1942.

Filed Feb. 19, 1940 4 Sheets-Sheet 2 IN VENTOR. $772351? [74%, BY 91 M 9% ATTORNEYS,

July 21, 1942. J FUNK. 2,290,423

AIR MOVING APPARATUS I Filed Feb. 19, 1940 4 Sheets-Sheet 5 INVENTOR. BY M [202%, @g A 9/M+W ATTORNEYS.

July 21, 1942. K

AIR MOVING APPARATUS Filed Feb. 19, 1940 4 Sheets-Sheet 4 220 300 $20 :10 am an 400 420 460 no 4w Patented July 21, 1942 UNITED STATES PATENT OFFICE 18 Claims.

This invention relates to an improved air moving apparatus and applications thereof.

The principal object of my invention is to provide an improved inlet and a centrifugal blower including a bafile on one side of the inlet opening projecting into the wheel on one side of the center and adjacent the cut-off point of the scroll housing, whereby to produce higher static pressure than has heretofore been obtainable in single stage blowers. The invention contemplates variation of the area of the inlet opening to increase or decrease the quantity of air handled and the static pressure, and also contemplates variation of the area of the baflle to vary the static pressure. The invention further contemplates rotary adjustment of the inlet plate so as to change the relationship of the inlet opening and baflie to the cut-ofi point of the housing to enable decrease in the static pressure and increase in the volume of air handled.

Another object is to provide an inlet plate of the kind mentioned of generally helicoidal form so as to give the air an initial twist as it enters the blower, thus reducing shock noise and btaining quiet erformance.

Still another object is to provide an inlet plate of the kind mentioned flanged longitudinally on the one side of the inlet opening internally and externally, the external flange coupled up with the helicoidal form of the plate inducing entrance of the air helically and the internal flange being more or less of an extension of the ballle to retain the air under static pressure.

The invention has numerous applications wherever a substantially constant capacity regardless of varying resistance is desired, one of the principal applications being its use in connection with underfeed stokers where changes in the fire bed result in a change in static pressure in the air conduit, the present blower by virture of its baflled or restricted inlet permitting such a bulid-up in static pressure in the blower itself and making it feasible to eliminate all of the automatic air controls heretofore considered essential, the operating characteristics of the present improved blower being also such that a much smaller sized blower can be used in any given installation as compared with the size of blower specified in combination with automatic air controls, thus appreciably lowering the aggregate cost of the installation besides eliminating much of the maintenance trouble and expense traceable heretofore to faulty operation of the automatic air controls used.

The present improved blower has also been applied to good advantage in industrial oil burners to deliver air at high enough pressure to effectively break up heavier oils, single stage blowers of the present type replacing double and even triple stage blowers in certain instances.

The invention may also be applied to suction apparatus, as, for example, vacuum cleaning devices, wherein the suction conduits are of course connected to the inlet opening and the present improvements are utilized to improve the efliciency of operation to substantially the same degree as in the other applications mentioned.

The invention is illustrated in the accompanying drawings, in which Fig. 1 is a side view of a blower embodying my invention; I

Figs. 2 and 3 area top view and end view, respectively, of Fig. 1; r

Fig. 4 is a vertical section through the blower on the line 4-4 of Fig. 2 on a smaller scale 3 Fig. 5 is an inside view of the inlet plate;

Figs. 6 and 7 are sections of said inlet plate in transverse planes taken on the correspondingly numbered lines of Fig. 1;

Fig. 8 is a horizontal section through the blower, taken on the broken line 8-8 of Figs. 1 and 4;

Fig. 9 is a section similar to Fig. 8, showing a larger baflie for increased static pressure;

Fig. 10 is a side view of a stoker installation utilizing the blower of my invention;

Fig. 11 is a side view of a typical stoker installation using an ordinary blower in combination with automatic air control mechanism, and

Fig. 12 is a set of performance curves showing the adaptability of the present blower to stokers,

the performance curves being superimposed on other curves showing the performance of a conventional blower of larger size used in connection with automatic air controls, as shown in Fi 11.

Similar reference numerals'are applied to corresponding parts throughout the views.

Referring briefly to Figs. 10, 11 and 12, Fig, 11

Q shows a stoker having a conventional hopper to store the coal which is fed through a conduit 5| into the bottom of the retort 52. The coal fed to the retort rises therein to maintain a desired depth of fire bed, the coal being fed from the hopper through the conduit by a screw in the usual way. The screw is driven through reduction gearing in the housing 53 by an electric motor, indicated in dotted lines at 54, the same being disposed behind the blower housing 55. Simultaneously with the feeding of coal to the retort, air is discharged tangentially from the housing 55 through the neck 56 into the air conduit 51 and conducted into the retort 52 whereby to supply sufficient air to the fire bed for good combustion. At 58 is indicated an automatically shiftable damper adapted to adjust itself to suit varying bed conditions. As this damper turns, the pointer 59 turns relative to the indicator plate 60. While the damper 58 may be operated by any suitabl automatic mechanism, the one herein shown has a link connection with an oscillating vane in the segmental housing Bl, The vane indicated in dotted lines at 62 tends to gravitate to the lowermost position, but it takes very little air pressure on the van to cause it to start rising and more and more pressure is required to raise the vane as it approaches horizontal position, at which position the damper 58 is substantially fully open. An air bleeder valve is provided at 63 for escape of air from the housing BI and is carefully regulated to control the movement of the vane 62 and accordingly secure proper functioning of the damper 5B. This air control functions automatically to compensate for varying fuel bed conditions. The thing that determines the position of the damper 58 is the static pressure in th conduit 51 which acts on the vane 62 to accordingly open the damper 58. Thus, for example, if finer coal than usual is fed to'the retort and the resistance to air flow is accordingly increased the damper 58 is opened wider to admit more air. The same is true if more than the usual amount'of clinker is left in the fire bed and the resistance to air flow through the bed is accordingly increased. other words, the automatic air control meters the volume of air required for any certain fuel bed with a view to obtaining proper combustion.

The objection to these automatic air controls is that they are more or less expensive, and while the particular type of air control shown in Fig. 11 has been more or less trouble free, it is well known that most other automatic air controls have not functioned satisfactorily. Another important objection has been that these automatic air controls have imposed such resistance to air flow through th air conduit that larger blowers than would otherwise be required have been necessary. The stoker installation shown in Fig. illustrates the application of my improved blower I0, which enables the elimination of the automatic air control required with the blower 55 shown in Fig. 11. The elimination of the aircontrol reduces resistance to air flow through the air conduit 29 leading to th retort 52 and consequently permits use of a smaller sized wheel than would otherwise be necessary. For example, a 6" wheel in one instance satisfactorily replaced a 9" wheel otherwise required with th automatic air control. Fig. 12 shows curves comparing the performance of a 6" x 3" wheel with the present improved inlet plate I6 as against the performance of a 9" x 1 /4" wheel used in conjunction with an automatic air control. The inlet plate 15 is more fully described hereinafter, but it will suffice for the present purpose to state that it has an inlet opening and has a bafile 32 projecting from the inner side thereof into the wheel 20 adjacent the cut-off point 24 of the blower housing to provide a restriction in the inlet as to permit building up static pressure in the air conduit well above the heretofore specified limits of a blower of this size, whereby to deliver a substantially constant volume of air to the fire bed regardless of varying fire bed conditions and consequent variation in resistance to air flow. Manifestly a stoker equipped with such a blower will be free from the service troubles heretofore traceable to the automatic air controls, there being no moving parts in the present construction apt to fail to move as intended, for any reason. The arrow at: indicates the direction of rotary adjustability of the inlet plate l6 for changing the performance of the blower to suit the requirements of different installations, the plate being shown, for example, in the position of highest obtainable static pressure and lowest air capacity, the adjustment in a clockwise direction resulting in the movement of the bafile 32 in a clockwise direction away from the cut-off point 24 for decreased static pressure and increased air capacity. The blower In of my invention is therefore extremely flexible in its adaptability to different types of stokers and stoker installations. As. indicated by the curves in Fig. 12, I may also provide a damper in the air conduit 29 adjustable to different positions so as to adapt a given sized blower to use with several different sized stokers. Such a damper is indicated at 3'! in the discharge neck of the blower H1 in Fig. 10, and is adjustable by means of an arm and set permanently in a given position by means of a screw 66 with respect to the fixed quadrant E1 on the side of the blower housing, However, it must be understood that dampers ordinarily are not used but may be used only as a compromise to avoid the necessity for making many different sizes of blowers. The best efficiency is obtainable where the blower is provided of a size to suit the given sized stoker and no restriction is used on the discharge side of the wheel.

Fig. 12 shows graphically the effect upon the operation of the blower when my improved inlet plate I6 is applied. The flat curve A--B shows the performance of a 6" x 3" wheel in a standard housing with a standard inlet in accordance with the N. A. F. M. code. 'The curve C-D, on the other hand; shows the performance of this same wheel in a blower housing constructed along the lines shown in Figs. 1 to 8 and having the improved inlet plate |6 thereon, this curve being produced with a damper restriction of 1.75". The other curves CD1 and CD2 show the performance of the same unit with damper restrictions of 1.25 and .50", respectively. Special attention is called to the fact that whereas this 6" x 3 wheel in a standard housing with a standard inlet is capable of developing only 1" static pressure, the present unit is capable of developing 3" static pressure. Superimposed on the curves just mentioned are other curves showing the performance of a9? x 1 wheel in a standard housing with a standard inlet but utilizing an automatic air control. The curve E-F shows the performance of the 9" x 1 4 wheel in accordance with the N. A. F. M. code. Curves GH1, GHz and (EH3 show the performance of this same unit in connection with an automatic air control, and special attention is directed to the fact that whereas the 9" x 1 wheel without the automatic air control is capable of developing approximately 1.86 static pressure, it is capable of developing only 1.50" static pressure with the automatic air control. In other words, the action of the automatic air control is diametrically opposite in that respect to the action of the inlet plate [6 of my invention.

The application of my improved blower to an oil burner is not considered necessary to illustrate, and the same is true of the application to a suction apparatus such as a vacuum cleaner. It will suffice to state that in the oil burner application the improved inlet plate I 6 with the baffle 32 thereon cooperating with the wheel 20 and cut-off point 24 of the blower housing results in as high pressure discharge as was formerly obtainable in two or even three stage blowers, and I have found in actual use of the blower on industrial oil burners that much heavier oils can be burned and much more efiiciently, the reduction in fuel consumption in one specific instance being as high as 41%. Apparently the air discharged under high pressure fully gasifies even the heavier oils and perfect combustion is obtained. In the application of the blower to the suction apparatus, such, for example, as a vacuum cleaner, where the resistance to flow will naturally vary considerably, the baflle 32 makes the present blower just as effective in building up suction as it is effective in building up static pressure in the other applications mentioned, the inlet under those conditions being connected with the suction conduit and the discharge with the dirt receiver. There are, of course, numerous other applications of the present blower, but the ones mentioned are thought to be suflicient to illustrate the novel characteristics of the blower of my invention.

Referring now to Figs. 1 to 8 for a better understanding of the blower III of my invention, II designates the scroll housing having a separate front portion I2 abutting the same, as indicated by the joint line I3, bolts I4 serving to fasten the front section in place. The front section I2 has a circular opening I5 in which the inlet plate It is mounted, the plate being preferably rotatable in said opening for rotary adjustment of the baffle 32 and inlet opening 30, as previously indicated. Screws I! are therefore entered into arcuate slots I'Ia in the rim of the plate and are arranged when tightened to clamp the plate in a desired position of rotary adjustment. The back wall of the housing I I has a bearing hole I8 therein in eccentric relation to the opening I5 and plate I6, and the shaft I9 projects through this bearing hole and serves to drive the centrifugal impeller or wheel 20 with the periphery thereof close to the cut-off point 24 of the housing I I which is adjacent the discharge opening 25. The wheel 20 consists of a disk 2| cast integral with the ends of circumferentially spaced impeller blades 22, the other ends of which are cast integral with a ring 23. A recess 26 is provided in the rear wall of the housing II to accommodate at least a portion of the disk 2!. The discharge opening 25 is at the inner end of a discharge neck 2'! onto which the air conduit 29, previously mentioned, is arranged to be attached. The housing II is given a tapered form by reason of the wedge-shaped construction of the front section I2, most clearly indicated in Fig. 2. The front and rear walls of the housing therefore converge toward the discharge opening 25, and I have found that this enables operation at much higher static pressure than would otherwise be possible, the air moving clockwise with the blades 22 of the wheel being crowded into a narrow space as it approaches the discharge opening 25.

The inlet plate I 6 is preferably cast in one piece to the desired substantially helicoidal form shown. The helix formation is given to approximately the one half Ita, and in the other half I6b, which is dished to join to the ends of the first half, the elongated inlet opening 30 is provided. One side of this opening is along a substantially diametrical line between the halves Isa and I6?) defined in part by the flange 3| and In part by the baflle flange 32, both formed integral with the inlet plate in a plane subtsantially normal thereto. The flange 3I has an externally projecting portion 3Ia and an internally projecting portion 3lb, whereas the flange 32 is entirely internal and is substantially coextensive with the internally projecting portion 3Ib of the flange 3|. The helix formation of the inlet plate gives the incoming air an initial twist, thereby reducing shock noise and accordingly obtaining quiet operation. The external portion 3Ia of the flange 3| confines the air and guides it along the closed portion I6a of the plate so that the air moves first radially inwardly in the direction of the arrow (1 and is then guided, as indicated by the arrows b and 0, into a helical path as it enters the inlet opening 38. The arrows d and e indicate the path taken by other air entrained with the air flowing helically through the inlet opening 30. The air on entering the wheel 29 is impelled to move in a circular path and a portion of it is thrown outwardly under centrifugal force between the blades 22, and the balance, by reason of impact with and sudden stoppage by the baffle 32, is compressed, and a major portion of this compressed air escapes directly betwee the blades 22 through the discharge opening 2?: the baflie 32 being adjacent the cut-off point 2 2 as clearly indicated in Fig. 4. The balance of the compressed air will find its way along the inner surface of the plate I6 behind the inner portion 3Ib of the flange 3| and will be carried with the air moving in the direction of the arrow ,1 (Fig. 4) toward the discharge opening 25. The marginal edge portion 34 of the plate It bounding the outer edge of the inlet opening 30 cooperates with the other half Ilia of the inlet plate to form an annular shroud between the peripheral bladed portion of the wheel 20 and the blower housing II to retain all of the air that has entered and passed through or around the wheel, the word around being used because it is believed that an appreciable amount of air entering the inlet opening 30 is entrained with the fast moving streams of air set in motion around the periphery ofthe wheel within the housing and does not therefore pass between the blades 22. The baffle 32, as indicated by the curves CD-CD2 in Fig. 12, enables building u to as high static pressure in a single stage blower as was heretofore considered possible only in two or even three stage blowers. The highest static pressure is obtainable with the baflle at the cut-off point 24 of the scroll housing. I may change the area of the battle to vary static pressure, as indicated at 32a on'the inlet plate I611 in Fig. 9, where the baflle is appreciably larger in area than the bafiie 32 shown in Fig. 8 to obtain higher static pressure. Variation in the area of the inlet opening 3t results in increase or decrease in air' handling capacity and consequent decrease or increase in static pressure. Rotation of the inlet plate It also has the effect of decreasing static pressure and increasing air handling capacity. Thus, with the baffle 32 in the position of maximum static pressure, illustrated in Fig. 4, there is minimum air handling capacity, but by turning the inlet plate IS in a clockwise direction so as to retract the baflie 32 with respect to the cut-off point 24 of the housing, I can obtain a reduction in static pressure and increase in airhandling capacity.

In certain cases, too, where noise is objectionable, there may be a compromise by turning the inlet plate to position the baffle 32 differently with relation to the cut-off.

The damper 31 is suitably pivoted, as at 38, in the blower housing in a position to provide an adjustable restriction for the discharge opening and has the means shown at 65-45! for securing the same in adjusted position. Such dampers are not ordinarily provided, but only under the circumstances previously mentioned, where a comprise is advisable in order to avoid the necesity for providing different sizes of blowers.

It is believed the foregoing description conveys a good understanding of the objects and advantages of my invention. The appended claims have been drawn with a view to covering all legitimate modifications and adaptations.

I claim:

1. Air supply and control means for a furnace having an air delivery conduit extending thereto, comprising a blower housing of scroll form having a tangential discharge neck communicating with the conduit to deliver air thereto at a substantially constant rate, an air impeller wheel rotatable in said housing adjacent the cut-off point thereof and having impeller blades in circumferentially spaced relation around the periphery thereof, and an air inlet for delivering a air to the eye of said wheel and having a single air trapping baflle projecting therefrom into the eye on that side of center adjacent the cutoff point of the housing, said bafile extending substantially radially from the central portion of said impeller wheel through a major portion of the distance between said central portion and the inner periphery of the blades of said wheel.

2. A structure as set forth in claim 1, in which means is provided to vary the position of said baffle to vary the static pressure obtainable.

3. Air supply and control means for a furnace having an air delivery conduit extending thereto, comprising a blower housing of scroll form having a tangential discharge neck communicating with the conduit to deliver air thereto at a substantially constant rate, an air impeller wheel rotatable in said housing adjacent the cut-off point thereof and having impeller blades in circumferentially spaced relation around the periphery thereof, and an air inlet for delivering air to the eye of said wheel and having a single air trapping bafile projecting therefrom into the eye on that side of center adjacent the cut-off point of the housing, the air inlet being defined by a wall having a helical form with the longitudinal axis of the helix substantially parallel to the axis of the wheel, whereby the entering air is given an initial twist, said bafile extending from the innermost discharge end of said helix substantially radially with respect to the wheel.

4. Air inlet and static pressure control means for a centrifugal air blower of the type comprising a scroll housing, with a tangential discharge neck and an air impeller wheel rotatable in said housing adjacent the cut-off point thereof and having impeller blades in circumferentially spaced relation around the periphery thereof, said means comprising a wall in spaced relation to and adjacent the air inlet side of the wheel, having an inlet opening provided therein and having a single portion projecting toward and into the wheel on that side of the center toward the cut-off point of the housing, said portion extending substantially radially from the central portion of said impeller wheel through a major portion of the distance between said central portion and the inner periphery of the blades of said wheel to serve as a bafile for building up static pressure in said wheel adjacent the cut-off point of the housing.

5. Air inlet and static pressure control means for a centrifugal air blower of the type comprising a scroll housing, with a, tangential discharge neck and an air impeller wheel rotatable in said housing adjacent the cut-off point thereof and having impeller blades in circumferentially spaced relation around the periphery thereof, said means comprising a wall in spaced relation to and adjacent the air inlet side of the wheel, having an inlet opening provided therein and having a single portion projecting toward and into the wheel on that side of the center toward the cut-off point of the housing to serve as a baffle for building up static pressure in said wheel adjacent the cut-off point of the housing, the wall having a generally helical form with the longitudinal axis of the helix substantially parallel to the axis of the wheel, said helix terminating at the inlet opening.

6. A structure as set forth in claim 4, wherein the wall comprises a separate plate rotatable with respect to the housing and adapted to be secured in different positions of rotary adjustment to vary the static pressure obtainable and the air handling capacity of the blower.

'7. Air inlet and static pressure control means for a centrifugal air blower of the type comprising a scroll housing, with a tangential discharge neck and an air impeller wheel rotatable in said housing adjacent the cut-off point thereof and having impeller blades in circumferentially spaced relation around the periphery thereof, said means comprising a wall in spaced relation to and adjacent the air inlet side of the wheel, having an inlet opening provided therein and having a single portion projecting toward and into the wheel on that side of the center toward the cut-off point of the housing to serve as a baffle for building up static pressure in said wheel adjacent the cut-off point of the housing, the wall having a generally helical form with the longitudinal axis of the helix substantially parallel to the axis of the wheel, said helix terminating at the inlet opening, and wherein the baflle coincides with the discharge end of the helix and is disposed substantially radially with respect to the wheel.

8. Air inlet and static pressure control means for a centrifugal air blower of the type comprising a scroll housing, with a tangential discharge neck and an air impeller wheel rotatable in said housing adjacent the cut-off point thereof and having impeller blades in circumferentially spaced relation around the periphery thereof, said means comprising a wall in spaced relation to and adjacent the air inlet side of the wheel,

having an inlet opening provided therein and having a single portion projecting toward and into the wheel on that side of the center toward the cut-off point of the housing to serve as a baffle for building up static pressure in said wheel adjacent the cut-off point. of the housing, the wall having a generally helical form with the longitudinal axis of the helix substantially parallel to the axis of the wheel, said helix terminating at the inlet opening, and wherein the baffle coincides with the discharge end of the helix and is disposed substantially radially with respect to the wheel, said wall having an external flange extending longitudinally of one edge of the helix portion terminating short of the discharge end of the helix portion.

9. Air inlet and static pressure control means for a centrifugal air blower of the type comprising a scroll housing, with a tangential discharge neck and an air impeller wheel rotatable in said housingadjacent the cut-01f point thereof and having impeller blades in circumferentially spaced relation around the periphery thereof, said means comprising a wall in spaced relation to and adjacent the air inlet side of the wheel, having an inlet opening provided therein and having a single portion projecting toward and into the wheel on that side of the center toward the cut-ofi point of the housing to-serve as a bafile for building up static pressure in said wheel adjacent the cut-off point ofthe housing, the wall having a generally helical form with the longitudinal axis of the helix substantially parallel to the axis of the Wheel, said helix terminating at the inlet opening, and wherein the baffle coincides with the discharge end of the helix and is disposed substantially radially with respect to the wheel, said wall having an internal flange extending longitudinally of the edge of the helix portion to the baffle to form with said baffle an air retaining wall.

10. Air inlet and static pressure control means for a centrifugal air blower of the type comprising a scroll housing, with a tangential discharge 7 neck and an air impeller wheel rotatable in said housing adjacent the cut-off point thereof and having impeller blades in circumferentially spaced relation around the periphery thereof, said means comprising a wall in spaced relation to and adjacent the air inlet side of the wheel, having an inlet opening provided therein and having a single portion projecting toward and into the wheel on that side of the center toward the cut-off point of the housing to serve as a bafiie for building up static pressure in said wheel adjacent the cut-off point of the housing, the wall having a generally helical form with the longitudinal axis of the helix substantially parallel to the axis of the wheel, said helix terminating at the inlet opening, and the bafile coinciding with the discharge end of the helix and being disposed substantially radially with respect to the wheel, said wall being formed to provide an annular portion extending radially beyond the periphery of the wheel to serve as a closure for the housing so as to retain in the housing air discharged and set in motion in the housing by the wheel.

11. In air moving apparatus, in combination, a housing, a rotary impeller within said housing, said housing having a wall of progressively varying radius with respect to the axis of rotation of said impeller, said impeller having its periphery disposed adjacent to said wall at the region of minimum radius of said wall, said housing having an outlet leading from the region of greater radius, said housing having a helically formed portion provided with an opening at the inner end of the helix for admitting air to the interior of said impeller, said helical portion directing the ingoing air toward that portion of the impeller adjacent that portion of the housing of minimum radius.

12. In air moving apparatus, in combination, a housing, a rotary impeller within said housing, said housing having a curved wall the radius of which varies progressively with respect to the axis 'of said impeller, said impeller being a hollow cylindrical member having peripheral impeller blades for directing air from the interior of said impeller to the exterior thereof, the periphery of said impeller being located adjacent to a portion of said curved wall of relatively short radius, said housing beingprovided with an outlet communicating with-said housing adjacent to a portion of said wall of relatively great radius, said housing being provided with an apertured portion that projects into the impeller on that side of centeradjacent' the outlet of the housing for admitting air into the interior of said impeller, said apertured portion being disposed in close proximity to the inner periphery of the impeller blades in the vicinity of that portion of the curved wall of relatively short radius and being of suificient size to occupy a major portion of the area in a radial-plane between the central portion of the said impeller and said inner periphery to block the return flow of air from said outlet to said inlet.

13. In air moving apparatus of the centrifugal blower type, in combination, a scroll type housing, a centrifugal impeller situated eccentrically within said housing so as to be in closest proximity to its cut-oil, said housing having an inlet and outlet, and a helix structure in said inlet projecting into the eye of said impeller to direct air helically thereto and to trap air within this impeller adjacent the cut-off point so as to-prevent air escaping back through said inlet whereby to insure its movement out of the housing through the said outlet,said inlet structure partly closing the eye of the impeller.

14. A centrifugal air blower, comprising a scroll housing having opposed side walls and a tangential discharge neck defining a cut-off portion at the inner end of said neck, an impeller wheel rotatably mounted in said housing for.rotation on an axis parallel to the longitudinal axis of said housing and disposed alongside the cutoff portion, said wheel having impeller blades in circumferentially spaced relation around the periphery thereof, said housing having an aperture in the side wall thereof adjacent the inlet side of the wheel, the opposite side wall of said housing being imperforate, and a cover plate for said aperture having an inlet opening therein for delivering air into said wheel inside the circle of the blades, said housing being formed so that the apertured side wall on the inlet side of the wheel is in divergent relation to the plane of the inlet side of the wheel and in'divergent relation to the opposite side wall behind the wheel, the latter wall being disposed substantially normal to the axis of rotation of said Wheel and in closely spaced parallel relation to the adjacent side of said wheel, said walls converging toward the discharge neck, and a single air bafile substantially parallel to the axis of said wheel and closely adjacent the impeller blades at a critical point with respect to the circumference of the wheel, said bafile being of sufficient size to occupy a major portion of the area in a radial plane between the central portion of said impeller and said inner periphery to prevent retrogressive flow of air with respect to the housing discharge neck in the rotation of said wheel.

15. Air supply and control means for a furnace having an air delivery conduit extending thereto, comprising a blower housing of scroll form having a tangential discharge neck communicating with the conduit to deliver air thereto at a substantially constant rate, an air impeller wheel rotatable in said housing adjacent the cut-off point thereof and having impeller blades in circumferentially spaced relation around the periphery thereof, an air inlet for delivering air to the eye of said wheel, and a 5 single air bafiie extending in a direction substantially parallel to the axis of the wheel and closely adjacent the impeller bladesat a critical point with respect to the circumference of the wheel, said bafile being of sufficient size to occupy a ma- 10 jor portion of the area in a radial plane between the central portion of said impeller and said inner periphery to prevent retrogressive flow of air with respect to the housing discharge neck in the rotation of said wheel. 7 i 16. Air inlet and static pressure control means for a centrifugal air blower of the type comprising a scroll housing, with a tangential discharge neck and an air impeller wheel rotatable in said housing adjacent the cut-off point thereof ando having impeller blades in circumferentially spaced relation around the periphery thereof, said means comprising a wall in spaced relation to and adjacent the air inlet side of the wheel, having an inlet opening provided therein, and ai single air bafile extending in a direction substantially parallel to the axis of the wheel and closely adjacent the impeller blades at a critical point with respect to the circumference of the wheel, said bafile being of sufiicient size to occupy a fen major portion of the area in a radial plane between the central portion of said impeller and said inner periphery to prevent retrogressive flow of air with respect to the housing discharge neck in the rotation of said wheel. 35

17. In air moving apparatus, in combination, a housing, a rotary impeller within said housing, said housing having a curved wall the radius of which varies progressively with respect to the axis of said impeller, said impeller being a hollow we cylindrical member having peripheral impeller blades for directing air from the interior of said impeller to the exterior thereof, the periphery of said impeller being located adjacent to a portion of said curved wall of relatively short radius, said housing being provided with an outlet communicating with said housing adjacent to a portion of said wall of relatively great radius, said housing being provided with an apertured portion that projects into the impeller on that side of center adjacent the outlet of the housing for admitting air to the interior of said impeller, and a single air baffle extending in a direction substantially parallel to the axis of the impeller and closely adjacent the impeller blades at a critical point with respect to the circumference of the impeller, said bafile being of sufficient size to occupy a major portion of the area in a radial plane between the central portion of said impeller and said inner periphery to prevent retrogressive flow of air with respect to the housing discharge outlet in the rotation of said impeller.

18. In air moving apparatus of the centrifugal blower type, in combination, a scroll type housing, a centrifugal impeller situated eccentrically within said housing so as to be in closest proximity to its cut-off, said housing having an inlet and outlet, and a, structure in said inlet to direct air helically into the eye of said impeller, said inlet structure partly closing the eye of the impeller, and including in combination therewith a single air bafile extending in a direction substantially parallel to the axis of the impeller and closely adjacent the impeller periphery at a critical point with respect to the circumference of the impeller, said bafile being of sufiicient size to occupy a major portion of the area in a radial plane between the central portion of said impeller and said inner periphery to prevent retrogressive flow of air with respect to the housing discharge outlet in the rotation of said impeller.

JAMES M. FUNK. 

